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Greenhouse, conservatory and houseplants

In the greenhouse

Pot up any Begonia, Gloxinia and Achimenes (see A. 'Show Off', left) that you started off earlier in the spring and are now large enough to re-pot.

Don’t forget to prick out seedlings before they get too crowded, and then to pot them on as individual plants as soon as they are large enough.

Make sure you give greenhouse plants more space as they put on new growth. This will help to prevent disease, and to contain early pest infestations.

Check if plants need watering at least every few days and seedlings will need daily attention.

Temperature

Maintain a minimum of 5°C (41°F) to prevent fuchsias, pelargoniums and other tender plants being killed by the cold. A higher temperature of at least 12°C (54°F) is needed for most tropical plants, which will require a greenhouse heater.

Remember that temperatures can still drop at night. Seedlings in particular object to wide temperature fluctuations and a heated propagator, or fleece cover, could be a cost effective answer if your greenhouse is mostly full of hardy mature plants.

Humidity

If the weather is warm and sunny, you may need to start damping down the floor of the greenhouse in the morning, splashing water over it will increase humidity levels in the whole glasshouse. This will help reduce problems with red spider mite which like a dry environment.

Deadhead Hippeastrum (amaryllis), leaving the flower stalks to die down naturally. Keep feeding and watering, and you may be treated to further flowers in August, as well as the normal blooms next winter. Alternatively, feed for a few weeks (to build up the bulb) and then reduce the watering, let the leaves die back, and allow the plants to dry out completely. The bulbs can be ‘rested’ like this under the greenhouse bench or in a cupboard if they are houseplants, to be brought out in late summer or autumn, for flowering the following winter.

Rest pot cyclamen that flowered over the winter, reducing watering until the foliage starts to die down. The pots can be placed under the greenhouse bench, or in cupboard if they are houseplants, to be started back into growth in late summer.